Mikkel Bundgaard

Typed polyadic pi-calculus in bigraphs

Bigraphs have been introduced with the aim to provide a topographical meta-model for mobile, distributed agents that can manipulate their own communication links and nested locations. In this paper we examine a presentation of type systems on bigraphical systems using the notion of sorting. We focus our attention on the typed polyadic π-calculus with capability types à la Pierce and Sangiorgi, which we represent using a novel kind of link sorting called subsorting. Using the theory of relative pushouts we derive a labelled transition system which yield a coinductive characterisation of a behavioural congruence for the calculus. The results obtained in this paper constitute a promising foundation for the presentation of various type systems for the (polyadic) π-calculus as sortings in the setting of bigraphs

A CPS encoding of name-passing in higher-order mobile embedded resources

We present an encoding of the synchronous π-calculus in the calculus of Higher-order mobile embedded resources (Homer), a pure higher-order calculus with mobile processes in nested locations, defined as a simple, conservative extension of the core process-passing subset of Thomsens Plain CHOCS. We prove that our encoding is fully abstract with respect to barbed bisimulation and sound with respect to barbed congruence. Our encoding demonstrates that higher-order process-passing together with mobile resources in, possibly local, named locations are sufficient to express π-calculus name-passing. The encoding uses a novel continuation passing style to facilitate the encoding of synchronous communication.

Modelling the Security of Smart Cards by Hard and Soft Types for Higher-Order Mobile Embedded Resources

We provide a type system inspired by affine intuitionistic logic for the calculus of Higher-Order Mobile Embedded Resources (Homer), resulting in the first process calculus combining affine linear (non-copyable) and non-linear (copyable) higher-order mobile processes, nested locations, and local names. The type system guarantees that linear resources are neither copied nor embedded in non-linear resources during computation. We exemplify the use of the calculus by modelling a simplistic e-cash Smart Card system, the security of which depends on the interplay between (linear) mobile hardware, embedded (non-linear) mobile processes, and local names. A purely linear calculus would not be able to express that embedded software processes may be copied. Conversely, a purely non-linear calculus would not be able to express that mobile hardware processes cannot be copied.

A CPS Encoding of Name-Passing in Higher-Order Mobile Embedded Resources

We present an encoding of the synchronous π-calculus in the calculus of Higher-Order Mobile Embedded Resources (Homer), a pure higher-order calculus with mobile processes in nested locations, defined as a simple, conservative extension of the core process-passing subset of Thomsens Plain CHOCS. We prove that our encoding is fully abstract with respect to barbed bisimulation and sound with respect to barbed congruence. Our encoding demonstrates that higher-order process-passing together with mobile resources in (local) named locations are sufficient to express π-calculus name-passing. The encoding uses a novel continuation passing style to facilitate the encoding of synchronous communication.